He had with him a weapon so small, so intangible, that even the most thorough search couldn't disclose it. Some time ago a surgeon at Washington, D.C. had sewn it into his tongue; a self-guiding, high-velocity poison dart, modeled on Soviet Russian lines... but vastly improved, in that once it had reached its victim it obliterated itself, leaving no remains...

All he needed to do was stand within arm's length of his intended victim and manually squeeze the base of his tongue, protruding the same simultaneously in the victim's direction...